AgI-ZrO2 and AgI-SiO2 composites were prepared using sol-gel derived aerogels. The conductivity at room temperature showed a maximum for the composition of 0.4AgI.0.6ZrO(2) or 0.4AgI.0.6SiO(2) and was 3.3 x 10(23) S cm(-1) for the composite using ZrO2 aerogels and 1.2 x 10(24) S cm(-1) for the composite using SiO2 aerogels. The diffusion of AgI into the micropores of the aerogel was observed for the ZrO2 system, suggesting that the diffusion caused a decrease of the crystallinity of AgI and the formation of a high conductive phase of AgI at the AgI-ZrO2 interface. In the SiO2-containing system, however, the diffusion was not observed and, hence, the conductivity was an order of magnitude lower than that of the ZrO2-based system.